Teledyne M300EM GFC Wheel Temperature, IR Photo-DetectorTEC Temperature, Electrical Shock Hazard

Troubleshooting & Repair Teledyne API – Technical Manual - Model 300E Family CO Analyzers

∙At room temperature it should have approximately 30K Ohms resistance; near the 48oC set point it should have ~12K ohms.

13.4.1.3.GFC Wheel Temperature

Like the bench heater above there are three possible causes for the GFC Wheel temperature to have failed.

1.The wheel heater has failed.

∙Check the resistance between pins 1 and 4 on the white five-pin connector just below the sample temperature sensor on the bench (pin 1 is the pointed end).

∙It should be approximately 275 ohms.

2.Assuming that the I2C bus is working and that there is no other failure with the relay board; the solid- state relay (K1) on the relay board may have failed.

∙Using the WHEEL_HEATER parameter under the signal I/O function, as described above, turn on and off K1 (D2 on the relay board should illuminate as the heater is turned on).

∙Check the AC voltage present between pin 1 and 4.

CAUTION

ELECTRICAL SHOCK HAZARD

Hazardous Voltages are present during this test

3.If the relay has failed there should be no change in the voltage across pins 1 and 4. ∙ K1 is socketed for easy replacement.

4.If K1 checks out OK, the thermistor temperature sensor located at the front of the filter wheel assembly may have failed.

5.Unplug the connector labeled “Wheel”, and measure the resistance of the thermistor. The resistance near the 68°C set point is ~5.7k ohms.

13.4.1.4.IR Photo-Detector TEC Temperature

If the PHT DRIVE test parameter described in Table 12-3is out of range there are four possible causes of failure.

1.The screws retaining the IR photo detector to the absorption bench have become loose.

∙Carefully tighten the screws, hand-tight and note whether, after the analyzer has come up to operating temperature, whether the PHT DRIVE voltage has returned to an acceptable level.

2.The two large transistor-type devices mounted to the side of the Absorption Bench have come loose from the bench.

∙Tighten the retaining screws and note whether there is an improvement in the PHT DRIVE voltage.

3.The photo-detector has failed. Contact the factory for instructions.

4.The sync demodulator circuit board has failed. Contact the factor for instructions.

286 04288D DCN5752